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This discussion relates to Technology Review's article Solar-Power Breakthrough.

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  mvpereira
  

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  08/01/2008 09:29 AM

  Petroleum (and others) enemy

  Nowadays people are conscious of individuals effects on Earth sustainability. This makes the new discovery amazing. Although I got really surprised with this discovery, I am really afraid energy companies that use petroleum and other cheap (at least for the moment) resources will try to postpone the application of such technology. They show themselves as good guys, but what they really want is to earn a lot of money. I really hope this doesn't happen, and it's just my imagination.

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  judbarovski
  

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  08/01/2008 09:31 AM

  i don'l see any advantage

  i don't see any advantave as against conventional water electrolysis in cost and materials. Besides Solar electricity can be as cheap as 1 cent per kwh
  (see http://judbarovski.livejournal.com/tag/analysis)

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  bj
  

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  08/01/2008 10:27 AM

  There's one huge logistical problem

  The places where Solar installations make the most sense are places where water is available least.
  
  This will so negatively affect cost of operation that I imagine that it will be very limited to the few places where it makes sense to deploy it.
  
  Though I do hope for the best, I'm remembering the great number of "Solar Breakthroughs" that, though they seemed to be fabulous ideas, never made it past the demonstration stage.

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  • 
    MyTrac
    

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    08/01/2008 02:11 PM

    Re: There's one huge logistical problem

    There is an immense opportunity implementing solar on rooftops. So if your home has water your good to go.

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    • 
      LDighera
      

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      08/06/2008 09:57 AM

      Re: There's one huge logistical problem

      "There is an immense opportunity implementing solar on rooftops."
      
      It would seem that Southern California Edison has embarked on doing just that:
      
      Click for article
      Southern California Edison Launches Nation's Largest Solar Panel
      Installation
      March 27, 2008
      Southern California Edison (SCE) today launched the nation's
      largest solar cell installation, a project that will place 250
      megawatts of advanced photovoltaic generating technology on 65
      million square feet of roofs of Southern California commercial
      buildings - enough power to serve approximately 162,000 homes.
      
      "These are the kinds of big ideas we need to meet California's
      long-term energy and climate change goals," said Governor
      Schwarzenegger. "I urge others to follow in their footsteps. If
      commercial buildings statewide partnered with utilities to put
      this solar technology on their rooftops, it would set off a huge
      wave of renewable energy growth."
      
      "This project will turn two square miles of unused commercial
      rooftops into advanced solar generating stations," said John E.
      Bryson, Edison International chairman and CEO. "We hope to have
      the first solar rooftops in service by August. The sunlight power
      will be available to meet our largest challenge - peak load
      demands on the hottest days."
      
      SCE's renewable energy project was prompted by recent advances in
      solar technology that reduce the cost of installed photovoltaic
      gen...

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  Siphon
  

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  08/01/2008 10:45 AM

  Thermodynamics

  No offense, but the 100% efficiency claim is snake oil. Reaction of H2 with O reduces entropy by reduction of gas molecules (O comes in O2 only), and as a result, even perfectly efficient catalysis cannot approach 100% efficiency. By a long run, actually. With perfect thermodynamic efficiency, they could get around 80%. Much less if you factor in the compressor and other parasitic system losses that are need in the elecrolysis system.
  
  I was under the impression that the MIT people understood the definition of entropy. Clearly I was wrong. I'm very disappointed now.

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    Kevin Bullis
    

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    08/01/2008 11:55 AM

    Re: Thermodynamics

    Siphon--Where did you see a 100% efficiency claim?

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      gvo1000
      

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      08/02/2008 09:28 PM

      Re: Thermodynamics

      Nocera has been quoted in other publications (e.g., eetimes) hyping 100% efficiency. As you'll see in the linked article, the non-expert writer laps that up. But Nocera's quote is "In fact, with our catalyst almost 100 percent of the current used for electrolysis goes into making oxygen and hydrogen." A clear case of shameless hype. In any electrolyzer, almost 100% of the current goes into making oxygen and hydrogen. It is the unavoidable overvoltage that cuts the net energy efficiency dramatically. So maybe his catalyst makes that a bit better, but he likes to leave that 100% impression, knowing full well that this 100% is achieved even in the most primitive electrolyzers kids build for their high school science projects.

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        Siphon
        

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        08/03/2008 10:17 AM

        Re: Thermodynamics

        Let's give them the benefit of the doubt and say they've got an 80% efficient (HHV) system. They would need a perfect compressor for that (and even then it's generous).
        
        Now, fuel cells are basically elecrolysers in reverse. So let's give them a generous 80% theoretical efficiency too.
        
        Let's even take a very generous total compression and other parasitic losses of 20%.
        
        This is probably more generous than the fundamental thermodynamic limits allow, and even then almost half of the energy is wasted. So even theoretically, hydrogen is still lossy. In practice losses are about twice that, and it's advancing only very slowly in real world testing.
        
        Hydrogen energy storage doesn't work. Let it be MIT...

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    smithsomian
    

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    08/01/2008 01:10 PM

    Re: Thermodynamics

    siphon, are you being stupid? nowhere was there a claim of 100% efficiency. we all know that is impossible. i could bet the researchers have gone through basic thermodynamics course (may even have wrote a textbook or two) to know that.

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    • 
      Siphon
      

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      08/03/2008 10:19 AM

      Re: Thermodynamics

      No you are stupid. In fact so stupid that you couldn't read the post above with the Eetimes link. And lazy too - you didn't even bother
      to google for it.
      
      You're lazy, stupid and insulting. At least I'm only the latter.
      
      The researchers have either been misquoted (I hope this is the case) or they really do not understand the definition of entropy. I really, really hope it's a misquote, but even then Nocera must realize the implications of low system efficiency, as this is related to entropy. This is the crux of the problem with hydrogen energy storage, and it's a killer for large scale market penetration.
      
      Hydrogen has it's uses: rocket fuel, chemical feedstock. An energy carrier is not part of this list.

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